KR101759488B1 - Combined magnet construction for DC motor - Google Patents

Abstract

A DC motor having a stator (10) and a rotor (20) is characterized in that: the magnet (30) is mounted on the receiving groove (25) of the rotor (20) (30) is characterized in that the N-pole portion (31) and the S-pole portion (32) are integrally formed in an arcuate shape via a connecting portion (35).
Accordingly, it is possible to reduce the required number of permanent magnets by half while maintaining the reduction in the performance of the DC motor to a minimum, thereby increasing the overall material cost and the utilization efficiency by reducing manufacturing costs.

Description

[0001] The present invention relates to a combined magnet structure for a DC motor,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnet structure of a DC motor, and more particularly, to a monolithic magnet structure of a DC motor that reduces the number of permanent magnets required for a DC motor in half, thereby reducing material costs and manufacturing costs.

In general, DC motors are capable of precise speed control, low noise and low power consumption, and BLDC motors (Brushless DC motors) are adopted in fuel pumps of vehicles to ensure high efficiency, long service life and reliability. Despite the excellent characteristics of the BLDC motor, the cost of the motor itself and power semiconductor devices are disadvantageous in terms of cost structure. In particular, an expensive rare earth magnet installed in the rotor of the BLDC motor causes an increase in the manufacturing cost as a whole.

Prior art documents which can be referred to in this connection are Korean Patent Laid-Open Publication No. 2011-0008533 (Prior Document 1), Korean Patent Laid-Open Publication No. 2000-0039493 (Prior Document 2), and the like.

The prior art document 1 has a cylindrical body; A first magnet portion formed on one side of the main body and having two magnetic poles along the longitudinal direction; And a second magnet portion formed on the other side of the main body and having two magnetic poles symmetrical with respect to the center of the main body. As a result, the monolithic magnet and the linear vibration motor having the monolithic magnet are not damaged by vibration or impact, and the operation life time is prolonged.

However, this is a structure that is not damaged by vibration and impact in a motor causing vibration of the mobile phone, and therefore, it is difficult to apply to a BLDC motor.

Prior Art 2 discloses a rotor of a permanent magnet-embedded brushless DC motor, which is formed by separate resin injection and is respectively coupled to both sides of a rotor core so as to support the permanent magnets so as not to be detached from the buried grooves, And a protrusion for preventing the permanent magnet from flowing. Therefore, the number of parts is reduced and the number of assembly operations is reduced, thereby reducing the cost of the motor.

However, since the brass support plate and the balance weight are replaced by a resin molding, it is difficult to expect a large cost reduction effect as a whole.

1. Korean Patent Publication No. 2011-0008533 entitled "Integral Magnet and Linear Vibration Motor Including It" (Published on Jan. 27, 2011). 2. Korean Unexamined Patent Application Publication No. 2000-0039493 entitled "Rotor of a permanent magnet-embedded brushless DC motor"

SUMMARY OF THE INVENTION It is an object of the present invention to overcome the above-mentioned problems of the prior art by providing an integral magnet of a DC motor, which reduces the required number of permanent magnets by half while maintaining a minimum reduction in the performance of the DC motor, Structure.

In order to achieve the above object, the present invention provides a DC motor having a stator and a rotor, wherein: the magnet is mounted on the receiving groove of the rotor at 2P (P = pole pair) And is formed as an integral arcuate shape.

In a detailed configuration of the present invention, the magnet has a symmetrical shape with the largest thickness at the center of the N pole portion and the S pole portion.

As a modification of the present invention, the magnet may further include a flux barrier for blocking magnetic flux in the connection portion.

In a detailed construction of the present invention, the magnet is characterized by having a bead protruding to increase a section modulus at a connecting portion.

According to another modification of the present invention, the magnet further comprises a reinforcing piece integrally formed in the inside of the connection portion to increase the mechanical strength and the impact resistance.

As described above, according to the present invention, it is possible to reduce the required number of permanent magnets in half while maintaining the reduction in the performance of the DC motor to a minimum, thereby improving the overall material cost and the utilization efficiency by reducing manufacturing costs.

FIG. 1 is a diagram showing a magnet according to the present invention,
2 is an enlarged view of a magnet according to the present invention;

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The present invention proposes, but is not necessarily limited to, a DC motor having a stator (10) and a rotor (20), particularly a brushless method. Brushless DC motors are advantageous for IPM applications, but not for SPM.

According to the present invention, the magnet 30 is mounted on the receiving groove 25 of the rotor 20 at 2P (P = pole pair) pole. 1 (a) and 1 (b) illustrate a DC motor composed of six poles. In the prior art, six magnets 30 are used as shown in FIG. 1 (a) The number of the magnet 30 is reduced. Since the thickness of the magnet 30 is reduced as a whole, the size of the receiving groove 25 formed in the iron core of the rotor 20 is also reduced.

According to the present invention, the magnet 30 is characterized in that the N-pole portion 31 and the S-pole portion 32 are integrally formed in an arcuate shape through a connecting portion 35. With reference to the six-pole motor of FIG. 1, one magnet 30 is formed in an arc shape extending over a range of about 120 degrees. The magnet 30 integrated with the N-pole portion 31 and the S-pole portion 32 on the other side is formed by the ferrite magnet manufacturing method, but the effect of cost reduction is further increased in the rare-earth magnet. It is possible to manufacture the magnetic powder by blending a predetermined magnet powder and a resin in a pressed state and then bonding or sintering. Surface treatment for enhancing physical properties such as corrosion resistance and heat resistance may be added depending on the use of the finished product (DC motor).

The magnet 30 has a symmetrical shape with the greatest thickness at the center of the N-pole portion 31 and the S-pole portion 32. In the present invention, The outer surface of the magnet 30 facing the stator 10 is formed with a constant curvature concentric with the rotation axis, but the inner surface is formed with a larger curvature to increase the thickness of the central portion. Accordingly, a structure advantageous for maintaining the mechanical strength and the coercive force due to the structure in which the thickness of the magnet 30 is reduced by 50% or more is provided. With this structure, the thickness of the connecting portion 35 connecting the N pole portion 31 and the S pole portion 32 becomes the thinnest.

The magnet 30 may further include a flux barrier 42 for blocking magnetic flux in the connection portion 35. [ By reducing the thickness of the connecting portion 35 and reducing the content of the magnet powder, it is possible to play the flux barrier 42 for concentration of magnetic flux density to some extent. For example, when the non-magnetic powder is concentrated in the connection portion 35, the leakage magnetic flux blocking function can be improved.

On the other hand, the conventional flux barrier 42 is advantageous in the form of pores for heat radiation, but when applied to the connection portion 35 in the magnet 30 of the present invention, serious mechanical strength deterioration is caused. However, after the thickness of the connecting portion 35 is increased, a large number of through holes are formed in the radial direction.

As a detailed configuration of the present invention, the magnet (30) is characterized by having a bead (44) protruding to increase the section modulus at the connection portion (35). A pair of beads 44 are formed to face each other on both sides of the inner surface connecting portion 35 of the magnet 30 in the city. The bead 44 increases the proof strength corresponding to the centrifugal force, the impact force, and the like generated in the rotation driving process of the motor, and restricts the unnecessary fluctuation of the magnet 30.

At this time, the beads 44 may be formed in the vertical direction as shown in the drawing, or in the circumferential direction orthogonal thereto.

The magnet 30 may further include a reinforcing piece 46 integrally molded in the connecting portion 35 to increase mechanical strength and impact resistance. Non-magnetic stainless steel, engineering plastic, or the like is used as the reinforcing member 46, and it is integrated by insert molding in the press forming process of the magnet 30. Accordingly, since the mechanical strength and the impact resistance are increased at the connecting portion 35 of the magnet 30, the reduction of the overall performance due to the reduction of the thickness of the magnet 30 is mitigated.

According to the structure of the present invention as described above, the material cost is reduced because the required permanent magnet size is reduced by half, but the effect of reducing manufacturing time by reducing the working time for mounting the magnet 30 on the rotor 20 is greater It is expected.

Meanwhile, although the present invention has been described based on a six-pole motor, the same principle can be applied to four poles and eight poles.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention as defined by the appended claims. It is therefore intended that such variations and modifications fall within the scope of the appended claims.

10: stator 20: rotor
25: receiving groove 30: magnet
31: N pole part 32: S pole part
35: connection 42: flux barrier
44: Bead 46:

Claims (5)

A DC motor having a stator (10) and a rotor (20) comprising:
The magnet 30 is mounted on the receiving groove 25 of the rotor 20 at a pole of 2P (P = pole pair)
In the magnet 30, the N-pole portion 31 and the S-pole portion 32 are integrally formed in an arcuate shape through a connecting portion 35,
The magnet 30 has a symmetrical shape with the greatest thickness at the centers of the N pole portion 31 and the S pole portion 32 and has an outer surface formed with a constant curvature concentric with the rotation axis,
The magnet (30) further includes a flux barrier (42) formed of a nonmagnetic powder to prevent magnetic flux from passing through the connecting portion (35)
Wherein the magnet (30) has a bead (44) protruding from the connecting portion (35) so as to increase a sectional modulus of the magnet (30). delete delete delete The method according to claim 1,
Wherein the magnet (30) further comprises a reinforcing piece (46) integrally molded inside the connecting portion (35) so as to increase mechanical strength and impact resistance.

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